Abstract: A light engine includes a housing, an optical assembly, a heat exchange device, and a fan. A first lens, a second lens, and the housing cooperatively define a first closed chamber. The first closed chamber includes an air-cooling chamber, a first heat exchange chamber, and a second heat exchange chamber. The first heat exchange chamber and the second heat exchange chamber are arranged on opposite sides of the light converging member, respectively. The air-cooling chamber is in communication with the first heat exchange chamber and the second heat exchange chamber. The liquid crystal light valve is arranged in the air-cooling chamber. A part of the heat exchange device is located in the first heat exchange chamber and/or the second heat exchange chamber. The air blower is provided in the first heat exchange chamber or the second heat exchange chamber.